I don't think we will ever go back to having more than one supplier personally. I don't see a hunger for it from teams, f1 or from suppliers.
I do think a change is needed though. For not only to get someone who can make decent wet tyres, but it will also help with throwing the balls up in the air and seeing where they land. Teams having to start from scratch to understand the tyres isn't a bad thing. We got some good races in the early Pirelli days.